1. Field of the Invention
The present invention relates to an apparatus configured to measure the film thickness of a film formed on a substrate on the basis of a plurality of imaged substrate images, a method of measuring the film thickness, and a non-transitory computer storage medium.
2. Description of the Related Art
In a photolithography process in a manufacturing process of a semiconductor device, for example, a series of treatments such as a resist coating treatment of applying a resist solution onto a wafer to form a resist film, exposure processing of exposing the resist film to a predetermined pattern, a developing treatment of developing the exposed resist film and so on are performed in sequence to form a predetermined resist pattern on the wafer. The series of treatments are performed in a coating and developing treatment system being a substrate treatment system including various treatment units that treat the wafer, transfer mechanisms that transfer the wafer and so on.
The resist pattern formed by the above-described photolithography processing defines the processing shape of a base film in a subsequent process in manufacture of the semiconductor device, and it is very important to form the resist pattern with a desired lien width.
One of causes affecting the line width of the resist pattern is the film thickness of the resist film. Therefore, in the photolithography processing, for confirming whether or not the film thickness of the resist film is uniform within a plane of the wafer, film thickness measurement of the resist film on the wafer after application of the resist is performed by a film thickness inspection apparatus.
For the measurement of the film thickness, for example, a reflectance spectroscopic film thicknessmeter as disclosed in Japanese Translation of PCT International Application Publication No. 2002-506198 or the like is used. This film thicknessmeter radiates light to a film being a measurement object and measures the film thickness from the wavelength or the like of its reflected light.
Incidentally, the film thickness measurement using the above-described reflectance spectroscopy or the like counts predetermined positions on the wafer as points, point by point and therefore, when performing the film thickness measurement in detail for the wafer entire surface, requires time of 30 minutes or more, for example, for one 300 mm wafer. Therefore, generally, for example, about 50 measurement points are set as representative points on the wafer, and the film thickness measurement is performed for the representative points to thereby implement quality confirmation of the film thickness.
However, there is a risk that a film thickness abnormality occurring at a point other than the measurement points cannot be detected in the measurement of the representative points, so that the measurement time and the quality securement are in a trade-off relation. Further, with an increase in diameter of the wafer size to 450 mm in recent years, the rate of points not measured in the case where the measurement at 50 points as in the prior art is performed significantly increases as compared with the case of the 300 mm wafer, thereby making it more difficult to balance the quality securement and the measurement time.